public void evaluate(final ExecutionContext ctx) {
   final ExecutionContext ctx1 =
       ctx.cloneWithVariable(
           new Variable(
               Advice.DEF_VAR_NAME,
               BuiltinMetaModel.DEFINITION_TYPE,
               new XpandDefinitionWrap(definition, ctx)));
   advice.evaluate(ctx1);
 }
 @Override
 public String toString() {
   return definition.toString() + " adviced by " + advice.toString();
 }